Many organizations and business are installing or using communication systems that use the Session Initiation Protocol (SIP). SIP communication systems provide many features that are not provided with other phone systems. Some of the features allow the communication system to interact with other computer-based applications. Thus, an application can trigger a phone call over the SIP communication system or execute other functions involving the SIP communication system.
Generally, these advanced features only function with SIP communication endpoints, that is, SIP phones connected to the SIP communication system. Thus, when a user receives a phone call from a communication endpoint, an “external device,” that is outside the internal network, the external device are not represented the same and require a wholly separate interface to provide the same features as the SIP-enabled phones. The additional interfaces are difficult and expensive to create. Because external devices are not treated similarly as the SIP-enabled, internal phones, SIP communication systems may not provide the most effective communication system.